Heyyy thank you for sharing. I downloaded the Rar and I read in the comments about opening it up in Notepad. So I opened in there and I just a whole bunch of mess. I am really confused on what to do next. Please Halp D:. Thank you.

I haven;t tried downloading brushes yet but I assume it's the same as when you download textures. In your SAI folder there should be an application called 'start-sai' it has a green icon with white/grey arrow shape. click that button to open SAI instead of opening it how you usually would. When SAI loads up the new brushes should be there.

Another thing to try, next to the button where you pick the pen brushes (the one's that's default is "(simple circle)", there's a scale (like when you choose the pen size) try moving it up to be on full, I downloaded some brush packs earlier and they wouldn't work unless the scale was up.I'm so bad at explaining things but I hope you understand that?